code: def _draw_slice(f, x, y=None, scale=True, shift=False):
      """plot a slice of a 2D function 'f' in 1D
  
      x is an array used to set up the axis
      y is a fixed value for the 2nd axis
      if scale is provided, scale the intensity as 'z = log(4*z*scale+1)+2'
      if shift is provided, shift the intensity as 'z = z+shift' (useful for -z's)
  
      NOTE: when plotting the 'y-axis' at fixed 'x',
      pass the array to 'y' and the fixed value to 'x'
      """
      import numpy
  
      if y is None:
          y = 0.0
      x, y = numpy.meshgrid(x, y)
      plotx = True if numpy.all(y == y[0, 0]) else False
  
      z = 0 * x
      s, t = x.shape
      for i in range(s):
          for j in range(t):
              xx, yy = x[i, j], y[i, j]
              z[i, j] = f([xx, yy])
      if shift:
          if shift is True:
              shift = max(-numpy.min(z), 0.0) + 0.5  # exact minimum
          z = z + shift
      if scale:
          z = numpy.log(4 * z * scale + 1) + 2
      # XXX: need to 'correct' the z-axis (or provide easy conversion)
  
      import matplotlib.pyplot as plt
  
      fig = plt.figure()
      ax = fig.gca()
      ax.autoscale(tight=True)
      if plotx:
          ax.plot(x.reshape(-1), z.reshape(-1))
      else:
          ax.plot(y.reshape(-1), z.reshape(-1))
      return fig
  
imports: from collections.abc import Callable
label_desc: Use image node_id 24 for calling a global function with example usage: _draw_slice(f, x, y, scale, shift) and returns: fig